the outer boundary of an artifact or a material layer constituting or resembling such a boundary | (physics) the curved upper surface of a nonturbulent liquid in a vertical tube |
a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight | (optics) a lens that is concave on one side and convex on the other |
a superficial aspect as opposed to the real nature of something | (anatomy) a disk of cartilage that serves as a cushion between the ends of bones that meet at a joint |
information that has become public | |
the extended two-dimensional outer boundary of a three-dimensional object | |
the outermost level of the land or sea | |